The present specification relates to displays. More particularly, the present specification relates to a head up display (HUD).
Display systems have been used to provide information to users for various applications. In aircraft applications, displays can provide precision guidance information to a pilot. For example, fixed head up displays (HUDs) include a fixed projector and a fixed combiner that conformally superimpose images from two sources, the outside world and an electronic image source for presentation to the pilot. HUDs are especially useful in aircraft because they allow the pilot to view information related to flight parameters without diverting attention from the view of the outside world through the windshield. Conventional fixed HUDs require optical components that can be heavy, expensive, and take up space in the cockpit. In addition, fixed HUDs are often difficult to fit into cockpit structures that have asymmetric and non-orthogonal shapes.
Wearable displays can be an alternative to fixed HUDs and generally include a visor, glasses or goggles that operate as combiner. Wearable displays are smaller and lighter than fixed HUDs, but are generally only used to show non-conformal information (airspeed, altitude, etc.). Accordingly, such wearable displays have limited usefulness in cockpit environments. Flight path, guidance, horizon, etc. on a conventional wearable display requires low-latency head tracking equipment.
One embodiment of the worn display discussed in U.S. application Ser. No. 14/700,557 provides head worn elements embodied as waveguides that couple light from a collimator fixed to the cockpit and deliver the light to the pilot's eyes without shifting the bore sight position. The embodiment requires no head tracking, and no electrical connectivity between the head worn waveguides and the aircraft. The wearable waveguides can be entirely passive and insensitive to all six degrees of freedom according to certain embodiments. Although embodiments of worn displays in U.S. patent application Ser. No. 14/700,557 provide significant advantages, worn displays have not been fully accepted by the non-military pilot community.
Thus, there is a need for a lower cost, lighter, and smaller fixed HUD. Further, there is a need for a fixed HUD having the size of a worn display and yet does not require connectivity (mechanical and/or electrical) between the combiner and the rest of the display system. Yet further still, there is a need for a fixed HUD where the combiner is located at a near eye position. Further still, there is a need for a display optimized for use in the constrained cockpit area of small aircraft that meets head impact criteria (HIC) requirements and is bright enough for daylight video. Even further still, there is a need for a fixed HUD that utilizes periscopic principles in the combiner. Yet further, there is a need for a near eye display that does not require head tracking and yet provides precision guidance information conformally aligned with the real world scene.
Accordingly, it would be desirable to provide a display system and/or method that provides one or more of these or other advantageous features. Other features or advantages will be made apparent in the present specification. The teachings disclosed extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned advantages or features.